# = digest/hmac.rb
#
# An implementation of HMAC keyed-hashing algorithm
#
# == Overview 
# 
# This library adds a method named hmac() to Digest classes, which
# creates a Digest class for calculating HMAC digests.
#
# == Examples
#
#   require 'digest/hmac'
#
#   # one-liner example
#   puts Digest::HMAC.hexdigest("data", "hash key", Digest::SHA1)
#
#   # rather longer one
#   hmac = Digest::HMAC.new("foo", Digest::RMD160)
#
#   buf = ""
#   while stream.read(16384, buf)
#     hmac.update(buf)
#   end
#
#   puts hmac.bubblebabble
#
# == License
#
# Copyright (c) 2006 Akinori MUSHA <knu@iDaemons.org>
#
# Documentation by Akinori MUSHA
#
# All rights reserved.  You can redistribute and/or modify it under
# the same terms as Ruby.
#
#   $Id$
#

require 'digest'

module Digest
  class HMAC < Digest::Base
    def initialize(key, digest_class, *digest_params)
      @digest_class  = digest_class.freeze
      @digest_params = digest_params.freeze
      @md = digest_class.new(*digest_params)
      @tmp_md = @md.clone

      block_len = @md.block_length

      if key.length > block_len
        key = @tmp_md.reset.update(key).digest
      end

      ipad = Array.new(block_len).fill(0x36)
      opad = Array.new(block_len).fill(0x5c)

      key.bytes.each_with_index { |c, i|
        ipad[i] ^= c
        opad[i] ^= c
      }

      @key = key.freeze
      @ipad = ipad.inject('') { |s, c| s << c.chr }.freeze
      @opad = opad.inject('') { |s, c| s << c.chr }.freeze
    end

    def initialize_copy(other)
      @md = other.instance_eval { @md }
    end

    def update(text)
      @md.reset.update(@opad + @tmp_md.reset.update(@ipad + text).digest)

      self
    end

    def reset
      @md.reset
    end

    def digest
      @md.digest
    end

    def digest_length
      @md.digest_length
    end

    def block_length
      @md.block_length
    end

    def inspect
      sprintf('#<%s: key=%s, digest=%s: %s>', self.class.name, @key.inspect, @tmp_md.reset.inspect, hexdigest());
    end
  end
end

if $0 == __FILE__
  eval DATA.read, nil, $0, __LINE__+4
end

__END__

require 'test/unit'

module TM_HMAC
  def hmac_new(key)
    Digest::HMAC.new(key, *digest_spec())
  end

  def test_s_hexdigest
    spec = digest_spec()

    cases.each { |h|
      assert_equal(h[:hexdigest], Digest::HMAC.hexdigest(h[:data], h[:key], *spec))
    }
  end

  def test_hexdigest
    cases.each { |h|
      hmac = hmac_new(h[:key])
      hmac.update(h[:data])

      assert_equal(h[:hexdigest], hmac.hexdigest)
    }
  end

  def test_reset
    cases.each { |h|
      hmac = hmac_new(h[:key])
      hmac.update("test")
      hmac.reset
      hmac.update(h[:data])

      p hmac
      assert_equal(h[:hexdigest], hmac.hexdigest)
    }
  end
end  

class TC_HMAC_MD5 < Test::Unit::TestCase
  include TM_HMAC

  def digest_spec
    [Digest::MD5]
  end

  # Taken from RFC 2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
  def cases
    [
     {
       :key		=> "\x0b" * 16,
       :data		=> "Hi There",
       :hexdigest	=> "9294727a3638bb1c13f48ef8158bfc9d",
     }, {
       :key		=> "Jefe",
       :data		=> "what do ya want for nothing?",
       :hexdigest	=> "750c783e6ab0b503eaa86e310a5db738",
     }, {
       :key		=> "\xaa" * 16,
       :data		=> "\xdd" * 50,
       :hexdigest	=> "56be34521d144c88dbb8c733f0e8b3f6",
     }, {
       :key		=> "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19",
       :data		=> "\xcd" * 50,
       :hexdigest	=> "697eaf0aca3a3aea3a75164746ffaa79",
     }, {
       :key		=> "\x0c" * 16,
       :data		=> "Test With Truncation",
       :hexdigest	=> "56461ef2342edc00f9bab995690efd4c",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key - Hash Key First",
       :hexdigest	=> "6b1ab7fe4bd7bf8f0b62e6ce61b9d0cd",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key and Larger Than One Block-Size Data",
       :hexdigest	=> "6f630fad67cda0ee1fb1f562db3aa53e",
     }
    ]
  end
end

class TC_HMAC_SHA1 < Test::Unit::TestCase
  include TM_HMAC

  def digest_spec
    [Digest::SHA1]
  end

  # Taken from RFC 2202: Test Cases for HMAC-MD5 and HMAC-SHA-1
  def cases
    [
     {
       :key		=> "\x0b" * 20,
       :data		=> "Hi There",
       :hexdigest	=> "b617318655057264e28bc0b6fb378c8ef146be00",
     }, {
       :key		=> "Jefe",
       :data		=> "what do ya want for nothing?",
       :hexdigest	=> "effcdf6ae5eb2fa2d27416d5f184df9c259a7c79",
     }, {
       :key		=> "\xaa" * 20,
       :data		=> "\xdd" * 50,
       :hexdigest	=> "125d7342b9ac11cd91a39af48aa17b4f63f175d3",
     }, {
       :key		=> "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19",
       :data		=> "\xcd" * 50,
       :hexdigest	=> "4c9007f4026250c6bc8414f9bf50c86c2d7235da",
     }, {
       :key		=> "\x0c" * 20,
       :data		=> "Test With Truncation",
       :hexdigest	=> "4c1a03424b55e07fe7f27be1d58bb9324a9a5a04",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key - Hash Key First",
       :hexdigest	=> "aa4ae5e15272d00e95705637ce8a3b55ed402112",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key and Larger Than One Block-Size Data",
       :hexdigest	=> "e8e99d0f45237d786d6bbaa7965c7808bbff1a91",
     }
    ]
  end
end

class TC_HMAC_RMD160 < Test::Unit::TestCase
  include TM_HMAC

  def digest_spec
    [Digest::RMD160]
  end

  # Taken from RFC 2286: Test Cases for HMAC-RIPEMD160 and HMAC-RIPEMD128
  def cases
    [
     {
       :key		=> "\x0b" * 20,
       :data		=> "Hi There",
       :hexdigest	=> "24cb4bd67d20fc1a5d2ed7732dcc39377f0a5668",
     }, {
       :key		=> "Jefe",
       :data		=> "what do ya want for nothing?",
       :hexdigest	=> "dda6c0213a485a9e24f4742064a7f033b43c4069",
     }, {
       :key		=> "\xaa" * 20,
       :data		=> "\xdd" * 50,
       :hexdigest	=> "b0b105360de759960ab4f35298e116e295d8e7c1",
     }, {
       :key		=> "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19",
       :data		=> "\xcd" * 50,
       :hexdigest	=> "d5ca862f4d21d5e610e18b4cf1beb97a4365ecf4",
     }, {
       :key		=> "\x0c" * 20,
       :data		=> "Test With Truncation",
       :hexdigest	=> "7619693978f91d90539ae786500ff3d8e0518e39",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key - Hash Key First",
       :hexdigest	=> "6466ca07ac5eac29e1bd523e5ada7605b791fd8b",
     }, {
       :key		=> "\xaa" * 80,
       :data		=> "Test Using Larger Than Block-Size Key and Larger Than One Block-Size Data",
       :hexdigest	=> "69ea60798d71616cce5fd0871e23754cd75d5a0a",
     }
    ]
  end
end